What ”software updates” can there be to make a mouse “new”? Are they adding camera functionality, text messaging or a toaster oven?
It's the code word for DRM.
Think about it for a second. Logitech can clearly sell a "forever" mouse with reliable hardware that lasts forever. They don't want to. They want to tie it to software.
If it were about software, they'd sell a software update only. Instead, it's clear they want software to control the hardware, just like Internet connection required HP printers with subscription ink.
If you don't pay, your mouse doesn't work anymore. Logitech is basically proposing a consumable item for a peripheral that should last for a decade.